1. Field
The present invention relates to a washing machine and a controlling method thereof. More particularly, the present invention relates to a washing machine and a controlling method thereof, capable of maintaining an optimal temperature for efficient generation of foam to perform foam washing that uses a large amount of foam in washing laundry, thereby accomplishing optimal washing efficiency.
2. Description of the Related Art
Generally, washing machines, especially drum-type washing machines, comprise a water tub to reserve detergent water or rinsing water therein, a cylindrical drum mounted rotatably in the water tub to receive laundry to be washed (hereinafter, referred to merely as “laundry”), and a motor to generate a driving force for rotating the drum. As the drum rotates, the laundry put in the drum repeats rising and falling along an inner wall of the drum, thereby being washed.
For this, such a washing machine performs a series of operation cycles including a washing cycle to separate dirt of the laundry by washing water containing detergent in solution, a rinsing cycle to rinse off foam and residual detergent from the laundry by rinsing water not containing detergent, and a dehydrating cycle to remove water from the washed laundry quickly. In the washing cycle, upon users' selection of a washing course, weight of the laundry is detected and an amount of washing water to be used is accordingly determined. Therefore, a proper amount of washing water to soak the laundry is put in the water tub together with detergent. The washing water containing detergent is distributed over the laundry by rotation of the drum, and the laundry is washed as rising and falling in the drum.
However, when using such a conventional washing machine, even a space between the water tub and the drum, as well as the inside of the drum, needs to be filled with the washing water. As a result, consumption of the water and the detergent increases. Heat washing presents further problems, as much energy is required to heat up the increased amount of supplied water.
In addition, a head by rotation of the drum and friction by water may seriously damage laundry of delicate cloths, such as silk, which require delicate washing.